1. Field of the Invention
The present disclosure relates to a medium detection device and an image formation apparatus including the same and, specifically to a medium detection device configured to detect a slack of a medium to be printed and an image formation apparatus including the same.
2. Description of Related Art
A conventional fixation device in an electrophotographic image formation apparatus includes a rotatable heat roller to fix toner to a printing medium such as paper by sufficiently fusing the toner on the printing medium. The heat roller includes a core metal having a hollow on the inside, a rubber layer formed on the outer surface of the core metal, and a halogen lamp provided in the hollow in the core metal, such that the rubber layer comes in contact with a first side of the printing medium on which a toner image is attached. Heat generated by the halogen lamp is transferred through the core metal to the rubber layer, and heats and fuses the toner image on the printing medium via the rubber layer.
A pressure roller is provided facing the heat roller, such that the printing medium having the toner image attached thereon is conveyed between the pressure roller and the heat roller while the first surface of the printing medium is pressed by the rubber layer of the heat roller. With this, toner forming the toner image is fused by the heat from the rubber layer and then fixed to the printing medium. After that, the printing medium having the toner image fixed thereon is discharged out of the image formation apparatus.
The image formation apparatus include a toner image transfer unit provided upstream of the fixation device and configured to transfer or attach the toner image to the printing medium. A medium detection device is provided to detect a slack of the printing medium, which is caused by the difference between a first medium conveyance speed of the image transfer unit and a second medium conveyance speed of the fixation device. Based on the detection by the medium detection device, the image formation apparatus controls the second medium conveyance speed of the fixation device in order to (1) prevent a slack of the printing medium, which may cause a jam of the printing medium and may cause scraping of the printing medium causing dirt in the image, and (2) prevent the printing medium from being over-tensioned between the toner image transfer unit and the fixation device which may cause an overload on a drive motor of the toner image transfer unit or the fixation device.
Japanese Patent Application Laid-Open No. 2006-92790 (Paragraphs 0018 to 0026 and FIGS. 1 and 4) discloses a medium detection device to detect a slack of a printing medium. The medium detection device is provided in a fixation device and includes a lever to be moved by the movement of the printing medium and a sensor to detect the movement of the lever.